Piperidine and its derivatives are ubiquitous building blocks in the synthesis of many naturally occurring products, pharmaceuticals and fine chemicals. In 2008, there were twenty one piperidine-containing drugs in Top 200 Selling Drugs, which showed sales of $11.2 billion (USD), with $2.5 billion for OxyContin (Purdue Pharma), $1.1 billion for the Concerta (Johnson & Johnson) and $0.31 billion for the Focalin XR (Novartis). In addition, Paxil (GSK), a chiral piperidine drug, had attributed total sales of $11.7 billion (USD) in 1997-2006.
Apart from the significant drug market, chiral piperidine compounds have also been studied extensively in both academic institutions and R&D sectors of pharmaceutical and biotechnology companies, due to their abundant presence as naturally occurring products which often have unique bioactivities, such as anopterine, pergoline, scopolamine and morphine, coniine, pipecoline, anabasine and anatabine, β-conhydrine, pipecolic acid, sedamine, indolizidine alkaloids and aza-sugars. As a result, the market for the chiral-piperidine based fine chemicals, which serve as building blocks for drug discovery and development, is of great significance and increasingly expanding due to the increasing demand mainly from pharmaceutical companies and generic drug producers.
While small chiral, cyclic amines such as piperidines are privileged chemical scaffolds, present in many natural products and pharmaceutical compounds1, approaches for the effective, atom economic synthesis of such compounds from simple starting materials are rare.
One attractive approach is the catalytic reduction of the parent heterocycles using hydrogen (H2) or another hydrogen source. Although much progress has been made in the asymmetric reduction of the more reactive benzofused heterocycles, direct synthesis of chiral piperidines by reduction of simple pyridine derivatives remains extremely challenging.2 
It is the aromatic nature of pyridine (resonance energy 27 kcal/mol), coupled with the tendency of pyridines to poison metal catalysts by coordination through the basic nitrogen atom, that makes the reduction of pyridines a particularly challenging task, typically requiring heterogeneous catalysts and forcing reaction conditions. As a result, the great advances made in homogeneous asymmetric hydrogenation have not been brought to bear, and a simple cost-effective asymmetric reduction of pyridines remains unrealised.2 
It is therefore an objective of the present application to provide a facile process for the formation of substituted piperidines.
It is a further objective to provide a facile process for the formation of chiral piperidines by the hydrogenation of pyridines.